127 results about "Magnetization curve" patented technology

A magnetic recording medium (10) has a substrate (12) and a perpendicular magnetic recording layer (30) formed over the substrate (12). The perpendicular magnetic recording layer (30) has a granular layer (20) in which a magnetic signal is recorded and a continuous film layer (24) magnetically coupled to the granular layer (20). The continuous film layer (24) has hard magnetic portions (204) formed in positions corresponding to the recording regions where magnetic signals are recorded in the granular layer (20) and magnetic shield portions (202) formed between the hard magnetic portions (204), each having a magnetization curve whose slope is larger than those of the hard magnetic portions in the region where the applied magnetic filed is zero when the magnetization curve is measured, and each having a residual magnetic polarization smaller than those in the hard magnetic portions.

The innovation points of the invention are that stator core is designed as E shape, and one fault tolerant tooth is added to each stator core. Winding is enwound on armature tooth and permanent magnet on two sides of E shaped stator core. There is no winding on fault tolerant tooth. Windings on radial opposite two poles are connected in series to constitute one phase. Fault tolerant tooth insulates phase windings. Excitation magnetic field is produced by permanent magnet. Fault tolerant tooth provides magnetic loop for permanent magnet and armature winding. The invention makes circuit, magnetic circuit, and temperature field independent between phase to phase of motor. The fault tolerant motor possesses higher reliability, and capability of operation under fault. Reducing width of gullet can reduce pulsation of torsion. Magnet core can run at inflection point of magnetization curve. The motor is especially suitable to areas of high reliability of continuous operation.

A soft magnetic ribbon that especially in a relatively low magnetic field region of 500 A / m or less, is high in the squareness of magnetic flux density-magnetization curve. There is disclosed a soft magnetic ribbon of 100 μm or less thickness comprising a parent phase structure in which by volume ratio, 30% or more of crystal grains of 60 nm or less (not including 0) crystal grain diameter are dispersed in an amorphous phase and comprising an amorphous layer disposed on the surface side of the parent phase structure. Preferably, the soft magnetic ribbon is represented by the composition formula Fe100-x-yCuxXy (wherein X is at least one element selected from among B, Si, S, C, P, Al, Ge, Ga and Be), in which the atomic percents (%) satisfy the relationships 0<x≦5 and 10≦y≦24.

The magnetic material for magnetic refrigeration of the present invention is characterized by exhibiting, in a certain temperature region, preferably, only in part of a temperature region from 200 K to 350 K, an inflection point at which a second order differential coefficient of a magnetization curve changes from positive to negative with respect to a magnetic field, within the range of this magnetic field formed using a permanent magnet unit. This magnetic material of the present invention can generate a low temperature by using a relatively low magnetic field, by transferring the entropy between the electron spin system and the lattice system near the temperature at which an inflection point appears on the magnetization curve. Examples of the magnetic material meeting this condition are La(Fe,Si)13, (Hf,Ta)Fe2, (Ti,Sc)Fe2, and (Nb,Mo)Fe2, each containing 50 to 60 atomic % of transition metals such as Fe.

The invention discloses a modeling method of an axial permanent magnetic motor equivalent magnetic circuit model. The modeling method includes the following steps of judging the topological structure which an axial permanent motor belongs to, determining the sizes of a stator, a rotor, a permanent magnet and an air gap of the motor, carrying out three-dimensional limiting element analysis on the axial permanent magnetic motor by means of limiting element simulation software to obtain magnetic flux density distribution of all portions of the motor, averagely dividing the axial permanent magnetic motor into N sections in the diameter direction, calculating equivalent magnetic resistance of the stator and the rotor according to magnetic flux density distribution obtained through limiting element analysis and magnetization curves of iron core materials of the stator and the rotor, calculating equivalent magnetic potential and equivalent magnetic resistance of the permanent magnet according to residual magnetism density of permanent magnetic materials and relative recoil permeability, dividing the air gap into a plurality of small areas according to the relative position of the stator and the rotor to calculate the equivalent magnetic resistance of all the portions, building the axial permanent magnetic motor equivalent magnetic circuit model according to modeling of all the portions. According to the modeling method, an accurate and quick magnetic circuit calculating method is provided for initialization and optimal design of the axial permanent magnetic motor.

The invention relates to a device for measuring internal stress of ferromagnetic material by pulse electromagnetic field. It is composed of detector, pulse electromagnetic field circuit and data acquisition and processing device, the detector part is composed of drive coil (7), heel piece (9) with one fieldpole and two measure poles and two groups of induction coil (8, 8'), weighing cell (4) is placed above the detector (5), the detector (5) is placed above the tested workpiece (6), which are clamped by jig; the pulse electromagnetic field circuit provides 1-3 Tesla strong incentive pulsed electromagnetic field for drive coil (7), the current signal in drive coil (7), the voltage signals of the two groups of drive coils (8, 8') are processed by data acquisition and processing device, then the magnetization curve and magnetic hysteresis loop of the tested workpiece (6) are obtained, after various kinds of magnetic parameters of the tested workpiece are determined, the rating curve between the internal stress and various kinds of magnetic parameters are established.

A magnetic recording medium includes; a base member; an underlayer formed on the base member; a main recording layer formed on the underlayer, and a writing assist layer formed on or under the main recording layer in contact with the main recording layer. The main recording layer has perpendicular magnetic anisotropy with an anisotropic magnetic field of Hk1 and an inclination of a reversal part of a magnetization curve of a1. The writing assist layer has an anisotropic magnetic field of Hk2 and an inclination of a reversal part of a magnetization curve of a2. The anisotropic magnetic fields Hk1 and Hk2 and the inclinations a1 and a2 satisfy Hk1>Hk2 ∞0 and a1>a2.

[PROBLEMS] To improve the track density by reducing the track edge noise and sharpening the boundaries of a recording magnetic field by blocking the recording magnetic field spreading outside the recording region in magnetic recording.[MEANS FOR SOLVING PROBLEMS] A magnetic recording medium (10) has a substrate (12) and a perpendicular magnetic recording layer (30) formed over the substrate (12). The perpendicular magnetic recording layer (30) has a granular layer (20) in which a magnetic signal is recorded and a continuous film layer (24) magnetically coupled to the granular layer (20). The continuous film layer (24) has hard magnetic portions (204) formed in positions corresponding to the recording regions where magnetic signals are recorded in the granular layer (20) and magnetic shield portions (202) formed between the hard magnetic portions (204), each having a magnetization curve whose slope is larger than those of the hard magnetic portions in the region where the applied magnetic filed is zero when the magnetization curve is measured, and each having a residual magnetic polarization smaller than those in the hard magnetic portions.

The invention relates to a measuring method for intensity of a magnetic field for inducing martensite phase transformation in steel under constant temperature. The measuring method comprises the steps of performing magnetism testing on a sample on a vibrating sample magnetometer of a comprehensive physical property measurement system after cutting the quenched steel sample into suitable sizes, drawing a hysteresis loop or magnetization curve of the sample under the constant temperature, observing and analyzing the measured hysteresis loop or magnetization curve, and determining intensity values of the magnetic field for inducing the martensite phase transformation under different testing conditions. The measuring method has direct guiding significance for determining a magnetic field processing process of quenched steel or using conditions under the magnetic field and can help accurately control structure forming and performance of the steel, and application potential of the steel is excavated.

The embodiment of the invention provides a transformer direct-current magnetic bias simulation method and device and relates to the field of transformer simulation. Real situations of a magnetization curve under the influence of direct-current magnetic bias can be simulated more precisely, and accordingly accurate simulation of distortion exciting current under direct-current magnetic bias is achieved on the basis of the magnetization curve. The method includes the steps that a direct-current bias flux density deltaB0 generated by direct current is calculated, and a Bm-deltaB0 curve is calculated, wherein Bm is work flux density of a transformer; according to the Bm-deltaB0 curve, a bias-free magnetization curve in a transformer model is corrected, and according to the corrected bias-free magnetization curve and the transformer model, the magnitude of exciting current, waveform and harmonic components in the transformer are determined. The method and device are used for simulating transformer direct-current magnetic bias.

Method and apparatus for measuring parameters in ferromagnetic steel structures, e.g. railway rails and drill pipes, to detect mechanical stress, damage and deterioration. On the monitored structure, devices for magnetization or demagnetization e.g. an electromagnet, will be installed. Two or more electrodes for feeding of a pulse shaped electrical voltage are installed. Across another pair of electrodes, a voltage response signal is measured, and compared with another response signal measured under known conditions or compared with calibration data for the structure. The deviation between these voltages is analyzed to quantify the relative or absolute deviations, and the condition of the steel structure is estimated. The device can measure the transient voltage curves with reference to one or more of the magnetization curves and includes algorithms for analyzing the voltage response curve for determination of mechanical stress and / or fatigue and / or cracks and / or metal loss in steel materials.

Provided are a test of adopting a random waveform power supply to measure voltage current characteristics of a mutual inductor and a calculation method. An accurate equivalent circuit of the mutual inductor is established, the method of adopting the random waveform power supply for testing the mutual inductor is put forward, and a group of calculation formula is deduced. The calculation method is suitable for tests of voltage current characteristic for electrical equipment with iron cores and coil structures such as a transformer, an electric reactor, a mutual inductor and the like, especially suitable for tests for a mutual inductor. By adopting the equivalent circuit, the test method and the calculation formula, various parameters of the mutual inductor such as hysteresis loss resistance, fundamental magnetization curve and core magnetization loop cluster can be measured with simple methods. By means of the parameters, test data of any frequency can be used for calculating test results of power frequency, calculation results and actual tested results of power frequency have good consistency, and the calculation method has the advantages of being simple, fast, convenient and safe in test.

The invention relates to an analysis method of a bias magnet characteristic of an electric sheet. According to design parameters and power input conditions, an independent Kirchhoff voltage and current equation set of an equivalent circuit is established, and the pressure drop of a cored winding is represented by a series connection form of a change rate dB / dt of magnetic density B, leakage inductance L and a winding resistance rL. In the analog computation, according to a typical hysteresis loop and a magnetization curve of ferrous materials, the maximum flux density Bm and the maximum coercive force Hc are determined, an initial value can start from zero and stepwise perform uplink increase or downlink increase according to history operating points which reflect the hysteresis characteristic in the hysteresis loop, another hysteresis loop process is started after one cycle period, and obtained delta B / delta t and H value of corresponding current must meet the Kirchhoff voltage and current equation set. A method of numerical approximation includes that under constraint conditions limited by the maximum hysteresis loops Bm and Hc, equal interval time delta t is used for simulating B-H tracks under any bias magnet conditions. The analysis method of the bias magnet characteristic of the electric sheet is simple in process and thinking, practical and convenient.

The present invention relates to a magnetic manipulation and navigation system for moving a magnetic element through a body comprising at least six electromagnets (24) with soft-magnetic cores arranged in a predetermined position to said body. It allows for the operation of one or more of the electromagnets in the non-linear regime of the magnetization curve of the cores. The system comprises at least one magnetic field sensor (104) at one or more predetermined positions outside of the operating region. While during operation in the linear region no feedback is required to set the magnetic field strength, during operation in the non-linear region feedback from the magnetic field sensors is used for closed-loop control. The system allows for operation in two separate modes, an open-loop mode operation in the linear regime for fast control signals such as they are required for stabilization during displacement of the magnetic element and a closed-loop operation in the non-linear regime for higher field strengths such as they may be required to apply forces and moments on the magnetic element while it is in contact with a surface.

The invention discloses a method for analyzing and calculating magnetic leakage coefficient of a built-in permanent magnet synchronous motor. The method comprises the following steps: supposing a value of the magnetic leakage coefficient, determining main magnetic flux of each electrode, and calculating the magnetic pressure drop of a main magnetic path based on the magnetic pressure drop of the main magnetic path, wherein the magnetic pressure drop is magnetic pressure drop added on the magnetic leakage path and a magnetic bridge part has high magnetic resistance, so the magnetic pressure drop is mainly added on the magnetic bridge part, and the magnetic field intensity of the magnetic bridge part can be determined; searching a magnetization curve according to the obtained magnetic field intensity of the magnetic bridge part to obtain the magnetic flux density of the magnetic bridge part, calculating the magnetic leakage flux, and evaluating the magnetic leakage coefficient according all the magnetic leakage flux; if the difference between the magnetic leakage coefficient and the supposed value exceeds a threshold value, resetting the magnetic leakage coefficient and repeating the above calculation process; if the difference value between the calculated value and the supposed value is within an allowable error threshold value, the calculated value is the obtained magnetic leakage coefficient. By the method, the magnetic leakage coefficient of the built-in permanent magnet motor can be calculated accurately and can be conveniently integrated into electromagnetic calculation adopting a magnetic path analysis method, and the accuracy of electromagnetic calculation is improved.

The invention relates to a device for mapping magnetizing characteristic curves of ferromagnetic materials and a mapping method thereof. The device comprises a hard magnetic sample, a soft magnetic sample, a case, a digital voltmeter UB, a UH, a power supply circuit of the UH, a waveband switch SB, connectors XS1 / XP1-XS8 / XP8, resistors Rx, Ry, a capacitor Cy and a panel. The mapping method comprises the following steps of switching on an electric source of the device, selecting the voltage input parameter of a signal generator and the mapping parameter of an oscillograph, demagnetizing the hard magnetic sample and the soft magnetic sample, scaling an X axis and a Y axis on the oscillograph and observing and mapping the fundamental magnetization curves and the magnetic hysteresis loops of the soft magnetic sample and the hard magnetic sample. The invention can respectively observe and map the dynamic magnetic hysteresis loops of the hard magnetic sample and the soft magnetic sample, is convenient for intuitively understanding and mapping the magnetizing characteristics of the hard magnetic sample and the soft magnetic sample, has high detection precision and compact structure and is used for researching the magnetizing characteristics of the ferromagnetic materials or electrical experiment teaching.

According to one embodiment, disclosed is a perpendicular magnetic recording medium in which a magnetic recording layer has a stacked structure including a hard magnetic recording layer and soft magnetic recording layer each having magnetic crystal grains and a grain boundary region. The magnetic crystal grains in the hard magnetic recording layer contain Co and Pt, have the hcp structure, and are orientated in the (0001) plane. The magnetic recording layer has a residual squareness ratio of 0.95 or less and an irreversible reversal magnetic field of 0 Oe or less on a magnetization curve when a magnetic field perpendicular to the substrate surface is applied.

The invention discloses a transformer direct-current magnetic bias analogue simulation method based on an improved J-A formula in a magnetic bias state, and relates to the field of Jiles-Atherton (J-A) hysteresis simulation modeling in the direct-current magnetic bias state. The method comprises the following steps: firstly, carrying out derivation correction on a J-A formula in a normal excitation state; based on the introduction of a direct-current component, improving a hysteresis-free magnetization curve and a differential expression of magnetization intensity of a J-A theory in a direct-current magnetic bias state according to a total current law and an energy conservation principle, correcting a containment coefficient k of the J-A theory, and providing an analogue simulation method;writing a simulation program in an S-function module of MATLAB (Matrix Laboratory) by using an M language; under the condition that winding end voltage and direct current are known, adopting simulinkto simulate an excitation current value and a hysteresis curve. The error between the excitation current value and the calculated value of the transformer direct-current magnetic bias model established based on the improved J-A formula is smaller. The hysteresis curve shape conforms to the character that the hysteresis curve of the single-phase transformer is similar to the step shape. The magnetization characteristic of the ferromagnetic material in the magnetic bias state can be better described.

The invention relates to a residual current detection method using magnetic core working state switch. Since the DC leakage signal does not fluctuate and the coil cannot induce the signal, it is necessary to superimpose the signal on an alternating signal. The method provided by the invention uses a chip to realize two states of the positive and negative square waves of the H-bridge circuit to achieve an external magnetic field, the bidirectional saturation excitation square wave signal enters the bidirectional saturation region of the magnetic core, the different characteristics are generatedby the DC in different regions of the magnetization curve, and the DC leakage detection and protection are completed by extraction and distinguishing with an algorithm. The AC leakage itself has fluctuations and works in the linear region of the magnetic core, so that the coil can directly sense signals including 50Hz, high-frequency AC 400Hz, 1kHz, 20kHz, 150kHz, etc. At this time, the coil is no excitation signal, and the data are extracted and calculated through the algorithm to complete AC leakage detection and protection. Three states of forward excitation, reverse excitation and no excitation are switched to complete the detection of complex residual current.

In a magnetic field analysis calculation, there is a need to consider a characteristic that a magnetic field and a flux density face in different directions from each other by a stress in a magnetic material. Therefore, a measured value of a magnetic characteristic on a condition that the magnetic field, the magnetic flux density, and a mechanical stress are parallel is used. In a method and a device for magnetic field analysis calculation, a stress magnetic anisotropy is calculated using a relation between a magnetostriction of the magnetic material, the magnetic flux density, and the stress and a relation between a magnetization curve of the magnetic material, the magnetic flux density, and the stress which are measured on a condition that the magnetic field and the stress in the magnetic material are parallel.

The invention relates to a measuring method for the remanence of a transformer iron core. The method comprises the steps that 1) the magnetization curve of the transformer iron core is acquired, wherein the magnetization curve reveals the relationship between the direct current component of no-load current and the remanence of the iron core; 2) 380V alternating current test voltage is applied to a transformer winding, and the no-load current is measured; 3) the direct current component of the no-load current is acquired; and 4) the iron core remanence is acquired according to the magnetization curve and the direct current component. Compared with the prior art, the measuring method provided by invention has the advantages that the method is simple and feasible, can quantitatively measure the remanence of the main transformer iron core, and guides the development of the degaussing scheme of the remanence of the main transformer iron core; the degaussing effect is evaluated; and a technical support is provided for the test and operation of a main transformer.

A method for analyzing the DC superposition characteristics of an inductance device using a magnetic field analysis simulator, comprising a first step of determining an initial magnetization curve from initial magnetization to saturation magnetization, and pluralities of minor loops at different operating points, on a toroidal core made of the same magnetic material as that of the inductance device, and obtaining point-list data showing the relation between magnetic flux density or magnetic field strength and incremental permeability from the incremental permeability at each operating point; a second step of determining an operating point at a predetermined direct current on each element obtained by mesh-dividing an analysis model of the inductance device by a magnetic field analysis simulator based on the initial magnetization curve of the core, allocating the incremental permeability to the operating point from the point-list data, and integrating the inductance of each element obtained from the incremental permeability to determine the inductance of the entire inductance device; and a third step of repeating the second step at different direct current levels to determine the DC superposition characteristics.

The invention discloses a magnetic property detection and analysis method of a permanent magnet material for a motor. The method comprises the following steps of subjecting a permanent magnet materialto be detected to saturated magnetization by a magnetization device and measuring the magnetization curve of the permanent magnet material to be detected; measuring the permanent magnet material to be detected by a measuring device; measuring a B signal and an H signal; inputting measured signal values into a computer, changing a magnetization current value in different ways, and drawing the demagnetization curve and the hysteresis loop of the permanent magnet material to be detected. The method measures the magnetic field strength, the magnetic induction intensity and the polarization intensity of the permanent magnet material to be detected by the measuring device, measures the complete parameter of the permanent magnet material to be detected, displays the demagnetization curve and thehysteresis loop of the permanent magnet material to be detected by the computer; improves the accuracy of magnetic performance detection, and avoids the use of permanent magnet materials with unqualified magnetic properties in the production of motors.

A method for preventing the unwanted maloperation of a protective relay system that is caused by the imprecise detection of an actual secondary current value resulting from a measured secondary current being distorted comprises the steps of calculating difference values for sampled secondary currents; comparing absolute values of the difference values with a predetermined critical value, and determining a saturation starting moment of a current transformer when one of the absolute values exceeds the predetermined critical value; obtaining a magnetizing current at the saturation starting moment using the difference values if the saturation starting moment is determined, and obtaining a magnetic flux value in a steel core of the current transformer from a magnetization curve using the magnetizing current; calculating a magnetic flux value at a time after the saturation starting moment using a secondary current value measured at that time and the magnetic flux value obtained at the saturation starting moment so as to obtain a secondary current value consistent with a current transformation ratio at that time; obtaining a magnetizing current at that time from the magnetization curve using the magnetic flux value calculated at that time; and obtaining the secondary current value consistent with the current transformation ratio by adding the obtained magnetizing current and the measured secondary current value.

A soft magnetic ribbon that especially in a relatively low magnetic field region of 500 A / m or less, is high in the squareness of magnetic flux density-magnetization curve. There is disclosed a soft magnetic ribbon of 100 [mu]m or less thickness comprising a parent phase structure in which by volume ratio, 30% or more of crystal grains of 60 nm or less (not including 0) crystal grain diameter are dispersed in an amorphous phase and comprising an amorphous layer disposed on the surface side of the parent phase structure. Preferably, the soft magnetic ribbon is represented by the composition formula Fe100-x-yCuxXy (wherein X is at least one element selected from among B, Si, S, C, P, Al, Ge, Ga and Be), in which the atomic percents (%) satisfy the relationships 0<x=5 and 10=y=24.